In the related art, a display device for measuring the shutter time lag of a camera is known (for example, NPL 1). In the display device disclosed in NPL 1, one turned-on LED sequentially switches among 100 LEDs at every predetermined time TD. That is, when the time TD elapses after an x-th (x is a natural number and 1≦x≦100) LED turns on and other LEDs turn off, the x-th LED turns off, and x+1-th LED turns on (LEDs other than the x+1-th LED turn off). As described above, the display device disclosed in NPL 1 starts the switching of a turned-on LED at every time TD in synchronization with the pressing down of a release button of the camera that is a target for measurement. It is possible to capture the images of the display device using the camera (the target for measurement) during the switching operation, and to deduce a shutter time lag from the pressing down of the release button to the image capturing based on the captured images. Specifically, it is possible to determine a turned-on sequence of the turned-on LEDs in the captured images, and to calculate the shutter time lag as the turned-on sequence x the time TD.